This invention relates to rotating union type coupling devices, and more particularly to multiple labyrinthine passage rotating unions.
Rotating unions are used in applications to couple the outlet of fluid sources to rotating devices. For example, rotating unions are used extensively in the paper processing industry, in high speed drilling and boring transfer operations, high speed machine tool spindles, clutch and brake operations, etc.
Multiple passage rotating unions have been provided for use with high-speed rotating machine parts that require two separate passages of media, or for carrying the same media at different pressures. Multiple passage rotating unions generally include a dual rotor assembly including an outer rotor and an inner rotor telescopically received within the outer rotor. The two rotors define separate fluid paths through the union from inlet ports formed in the union housing to outlet ports formed in the rotor assembly through which the fluid is conducted to the work piece with which the rotating union is associated. The rotor assembly is supported within the housing by one or more bearings which may be ball bearing assemblies, Oilite type bearings or by a composite Teflon bearing. Suitable seals must be provided within the housing to prevent cross-passage leakage. Generally, two seal assemblies are required for each passageway of the rotating union. Because such seals are susceptible to wear, provision must be made, such as providing vent holes, to prevent cross-passage leakage when the seals eventually wear out. Also, additonal machining of the housing and rotor is required to define mounting shoulders for the fluid seals and the seal retainers which isolate the fluid passageways from one another within the interior of the union housing. These requirements complicate the fabrication of both the housing and the rotor.
It would be desirable to have a multiple passage rotating union which is characterized by an extended lifetime as compared to multiple passage rotating unions presently available. It would also be desirable to have a multiple passage rotating union which is of simpler construction than multiple passage rotating unions presently available.